1. Field of the Invention
The present invention relates to a lens barrel enabled to adjust the position of an optical axis of a frame member and/or the inclination of the optical axis thereof.
2. Description of the Related Art
A conventional lens adjusting device for correcting misalignment of the center of an optical axis of a lens according to a utility model relating to a lens frame is proposed in the Japanese Utility Model Laid-Open No. 60-150511 Official Gazette, utilizes rotatable eccentric screws or pins. This conventional device has an adjusting structure including plural notch portions, each of which is provided in an outer periphery of the lens and engaged with an eccentric pin. The aforementioned device causes a micro-movement of the lens in a direction perpendicular to the optical axis thereof by rotating the eccentric pins, so that the centering of the lens is achieved.
However, the conventional device proposed in the Japanese Utility Model Laid-Open No. 60-150511 Official Gazette requires plural eccentric pins and is thus disadvantageous in its cost. Further, it is necessary for moving the lens in the direction perpendicular to the optical axis to simultaneously or alternately rotate plural eccentric pins. Therefore, the conventional device has a drawback in that it is difficult to perform the centering of the lens. Moreover, in the case of some support structure for the lens, there is the possibility that when the eccentric pins are rotated, the optical axis of the lens does not simply perform translation but inclines.
Furthermore, a conventional method of assembling a lens system for correcting the misalignment of the lens frame, which includes the inclination of the optical axis thereof, is proposed in the Japanese Patent Laid-Open No. 59-68710 Official Gazette. According to this conventional method, a lens system is assembled, and aligned by correcting the misalignment of the inclination of the optical axis of a lens that is held adjacent with other lenses by space forming rings, and by subsequently bonding the lenses with the space forming rings on the outer periphery thereof and fixing the lenses thereon.
In the case of the assembling method proposed in the Japanese Patent Laid-Open No. 59-68710, there is the probability that the optical center is changed simultaneously with adjusting the inclination of the optical axis of the lens. Hence, the adjustment of only the inclination of the optical axis of the lens cannot be performed. Further, even in the case of adjusting the inclination and position of the optical axis of a lens, both the inclination and position thereof simultaneously change, as described above. Thus, this conventional method has a drawback in that it is difficult to perform such an adjusting operation.
Moreover, a semiconductor laser light source serving as a device including an optical axis position adjusting structure of a support portion (namely, a frame portion) for supporting an optical component is disclosed in the Japanese Patent Publication No. 61-46895 Official Gazette, which device has an optical axis position adjusting structure that can perform fine adjustment of the optical axis position of a frame portion for supporting a semiconductor laser chip. FIG. 40 is an enlarged diagram illustrating the concept of the optical axis position adjusting structure.
In the optical axis position adjusting structure, a frame portion 311b for holding a laser light source portion acting as an optical component is supported against a support portion 311a through an elastically deformable cantilever-like plate spring portion 311c. When a side of a lens frame portion 311b is pushed by exerting a pressing force F0 thereon so as to adjust the optical axis position in the lateral direction of the optical component, the optical axis position Z0 is displaced leftwardly, as viewed in this figure, to a position Z1, to which the optical axis position is adjusted, by a movement amount xcex4x0.
However, simultaneously, the optical axis position is displaced upwardly or downwardly by a movement amount xcex4y0, so that the adjustment of the optical axis position in the upward or downward direction is necessary. Furthermore, when the center of the optical axis is moved from the position Z0 to the position Z1, the optical component rotates around the optical axis. This adversely affects the entire optical system. Thus, this conventional device has a drawback in that the adjustment of the optical axis position cannot be favorably achieved.
The present invention is accomplished to eliminate the aforementioned drawbacks of the prior art. Accordingly, an object of the present invention is to provide a lens barrel, which reliably and easily achieves the adjustment of an optical member, by operations that center and adjust the optical axis of the optical member.
In one form thereof, the objects of the invention are realized with the lens barrel which comprises a first frame and a second frame, at least one of which holds an optical device, e.g., a lens. The first frame has respective first and second frame portions and the second frame has respective third and fourth frame portions.
Associated with the first frame is a first adjusting member that is constructed to move either the first or the second frame portion in a direction that lies in a plane that is substantially orthogonal to the optical axis of the lens barrel. A respective second adjusting member performs a similar function for the second frame.
In accordance with preferred embodiments, the adjusting members can be in the form of a threadable screw whose threading direction extends orthogonally to the optical axis of the lens. The adjusting directions of the first and second adjusting members may preferably be orthogonal to one another.
In accordance with preferred embodiments, also included is a guide frame that movably guides at least one of the first and second frames in the direction of the optical axis. The first and second frames are constructed to be insertable into the guide frame, which is so constructed as to allow access to at least one of the first and second adjusting members from outside of the guide frame.
A cam ring can be provided in which the first frame and the second frame are receivable, one behind the other, with the cam ring being in turn receivable within the guide frame. The first and second frames may comprise respective cam followers and the cam followers are receivable within guiding slots in the guide frame.
Thus, the adjusting members deform first and second connecting portions that connect the first and second frame portions and the third and fourth frame portions, respectively. By this action, the frame portions are translated in planes that are substantially orthogonal to the optical axis without causing rotational displacement of the frame portions.